1. Field of the Invention
The present invention relates to a multilayer ceramic electronic component, such as a multilayer ceramic capacitor, and a method for manufacturing the multilayer ceramic electronic component. In particular, the present invention relates to a multilayer ceramic electronic component in which, even when laminated inner electrode layers and/or ceramic layers are thin films, the inner electrode layers are electrically connected to an outer electrode with reliability, and also the present invention relates to a method for manufacturing the multilayer ceramic electronic component.
2. Description of the Related Art
In recent years, further reduction in the size and the height profile of a multilayer ceramic electronic component, such as a multilayer ceramic capacitor, has been required. Thus, it is necessary to further reduce the thickness of an inner electrode, the thickness of a ceramic layer between the inner electrodes, and the like.
A known method for manufacturing a multilayer ceramic electronic component is described below. First, desired patterns of conductive paste containing nickel powder and the like are printed on ceramic green sheets. The plurality of ceramic green sheets with printed patterns of conductive paste are laminated to produce a laminated structure, a ceramic green sheet without conductive paste is laminated on each of a top and a bottom of the laminated structure, and thus a multilayer body is produced. After the produced multilayer body is pressed in the thickness direction, it is fired, and a ceramic sinter is thus obtained. Then, an outer electrode is formed on each of both end surfaces of the ceramic sinter, and a multilayer ceramic electronic component is thus obtained.
A known method for manufacturing a multilayer ceramic electronic component is also disclosed in Japanese Unexamined Patent Application Publication No. 2004-014634. FIG. 7 is a cross-sectional view that schematically illustrates a configuration of a multilayer ceramic electronic component manufactured by the known manufacturing method. As illustrated in FIG. 7, outer electrodes 3 and 4 are formed on both end surfaces of a ceramic sinter 2. Inner electrodes 5 made of conductive paste containing, for example, nickel powder, are arranged in the ceramic sinter 2 such that they overlap each other with ceramic layers disposed therebetween.
In the method for manufacturing the multilayer ceramic electronic component disclosed in Japanese Unexamined Patent Application Publication No. 2004-014634, the inner electrodes are exposed to the end surfaces of the ceramic sinter by oxidizing and expanding the inner electrodes in firing the multilayer body. However, it is difficult to adjust the degree of oxidation and expansion. In addition, because the inner electrodes and the ceramic layers have different shrinkage ratios in firing and typically the shrinkage ratio in the inner electrodes is large, the inner electrodes may be shrunken in directions separated from the end surface of the ceramic sinter by firing. In particular, when the inner electrodes are thin, they become separated more easily from the end surfaces of the ceramic sinter, and a problem arises in that it is difficult to ensure electrical connection with the outer electrodes.
That is, if the inner electrodes significantly shrink in directions separated from the end surfaces of the ceramic sinter, even when the end surface of the ceramic sinter are both polished by barrel polishing, for example, the inner electrodes may not be exposed through the end surfaces of the ceramic sinter. In such a case, it is impossible to ensure electrical connection between the inner electrodes and the outer electrodes.